1. Field of the Invention
The present invention relates to a head support structure in which a head is pressed against a sheet material transported by a platen roller when printing is performed on the sheet material, and also relates to a printing device, a thermally activating device, and a printer, which are equipped with the head support structure.
2. Description of the Related Art
Up to now, there is known a printer, which is called a thermal printer, for heating a sheet material to perform printing, for example. Such the thermal printer supports a thermal head for heating a heat-sensitive printing layer of the sheet material and includes a head support structure for pressing the thermal head against the sheet material.
As a conventional head support structure, as shown in FIGS. 14A and 14B, there is disclosed a structure including a thermal head 111, a head support member 113 for supporting the thermal head 111, a plurality of compressed coil springs 114 for biasing the head support member 113 to a platen roller 112 side, and a lock arm 115 for holding the platen roller 112 at a position where the platen roller 112 is pressed against thermal head 111 side (see, for example, JP 2003-200624 A).
In the conventional head support structure thus constructed, the head support member 113 and the lock arm 115 are rotated around a rotation shaft 119 and the head support member 113 is pressed by the compressed coil springs 114 each generating a biasing force, whereby the thermal head 111 is pressed against the platen roller 112 while nipping a sheet material therebetween. Further, a rotary shaft 118 of the platen roller 112 is engaged to a holding part 115a of the lock arm 115 when the thermal head 111 is pressed against the platen roller 112, whereby a state where the platen roller 112 is held is established.
The above-mentioned thermal printer is desired to be further downsized. However, the conventional head support structure includes a plurality of compressed coil springs for biasing a head support member which supports a thermal head to a platen roller side, and a lock arm for holding the platen roller at the position where the platen roller is pressed against the thermal head side.
Accordingly, as shown in FIGS. 14A and 14B, in the conventional head support structure, it is necessary to provide a portion in which the compressed coil springs 114 are arranged to elastically deform the head support member 113 in a direction in which the head support member 113 is pressed against the platen roller 112 side. As a result, a portion opposed to the head support member 113 which is opposite to the platen roller 112 side is occupied by the compressed coil springs 114. That is, since the lock arm 115 and the compressed coil springs 114 take up too much space in the conventional head support structure, it is difficult to downsize an entire apparatus to which the head support structure is mounted.